Hello,
Intro

The goal of this post if to gather as much information as possible about the CS2 graph. I'm facing most of the issue that you guys have, i am in the same situation as you; but let's try to keep this post as constructive / informative as possible and please no rent on how bad the game is, etc.
If you have no data to share; please avoid commenting.
My situation

In my situation since i got fiber I noticed that in the CS2 Margin Graph i have frequent yellow lines, those were not present when i had coax cable. The more yellow lines the less responsive my input feels (delayed strafe on keyboard) and delayed mouse input, in general everything will be delayed. Both my jitter are at 0ms straight lines but the gameplay feels very choppy and delayed, even though i have 500+ FPS on a 360Hz Zowie monitor.
Data

In order to test and have the full pictures inside CS2 go to :
Your settings --> Game --> scroll at the bottom --> put ALWAYS on the 5 settings in Telemetry or apply those 4 commands in CS2 console
cl_hud_telemetry_frametime_show 2
cl_hud_telemetry_ping_show 2
cl_hud_telemetry_net_misdelivery_show 2
cl_hud_telemetry_serverrecvmargin_graph_show 2
Here are my results :
Fiber :

- Fiber
- 1.png (23.18 KiB) Viewed 901 times
coax:

- coax
- 2.png (40.1 KiB) Viewed 901 times
my downstream and upstream jitter on fiber are on 0ms :

- 0ms jitters (on fiber)
- jitters.PNG (27.75 KiB) Viewed 901 times

If you are on fiber or you think you have CS2 issues related to network please apply the commands and check the Margin Graph (should be the lowest graph on top right corner of your monitor) and share the results here.
make sure that you test on multiple server and locations. My results are the same no matter the server and location.